Well it's actually forbidden to surcharge debit cards and echeck, so you may want to make sure those surcharges do not show on those payment types. You would get many of your clients put on the TMF (terminated merchant file) otherwise and then they wouldn't be able to accept cards at all.
The real problem with this is that current gateways do not specify debit or credit on checkout. Until the transaction is processed there is no way to tell from your processor which type of card it is for the purpose of the surcharge. So the real prblem is when customers just checkout as a credit and use their debit card, which again will get your business put on the TMF.
Again you also have to advertise that you surcharge on your website or retail store, it's also required to provide written notice of this to the card brands prior. If people are using something like stripe that's a 2.9% surcharge, in conjunction with US state sales tax being added to eCommerce orders recently it will divert your clients, and businesses will find many more abandoned carts.
